1. Field of the Invention
This invention relates generally to air purification processes, and more particularly to processes for regenerating adsorbents used in the removal of solvents and other contaminants from solvent laden air (SLA) streams.
2. Description of the Prior Art
Solvents are commonly removed from a SLA stream through contact with an adsorbent such as activated carbon. When the adsorbent becomes saturated or nearly saturated with solvent, the adsorbent is regenerated using steam to heat up the adsorbent and displace the solvents. The steam and solvents leave the adsorber and are condensed. Two layers form if the solvents are insoluble in water. In this case, the solvents may be separated from the water by decantation. If the solvents are soluble in water, there will not be any separation, and the solvents must be separated from water by other means such as distillation.
Prior art regeneration processes require that the water layer from decantation be further treated by air stripping or steam stripping to remove the solvents which remain in the water layer before the water is discharged to the sewer. Government standards require the removal of solvents from these effluent water streams prior to sewering these streams. The removal of solvents from water exiting regeneration processes is expensive. Treatment is particularly expensive when the solvents are soluble in water.